Aspirin activation of eosinophils and mast cells: implications in the pathogenesis of aspirin-exacerbated respiratory disease

Mast Cells in Aspirin-Exacerbated Respiratory Disease

PURPOSE OF REVIEW

Aspirin-exacerbated respiratory disease (AERD) is a syndrome of high type 2 inflammation and is known to critically involve mast cell activation. The mast cell is an important cell in the baseline inflammatory processes in the upper and lower airway by maintaining and amplifying type 2 inflammation. But it also is prominent in the hypersensitivity reaction to COX-1 inhibition which defines this condition.

RECENT FINDINGS

Recent work highlights the mast cell as a focal point in AERD pathogenesis. Using AERD as a specific model of both high type 2 asthma and chronic sinusitis, the role of mast cell activity can be better understood in other aspects of airway inflammation. Further dissecting out the mechanism of COX-1-mediated mast cell activation in AERD will be an important next phase in our understanding of NSAID-induced hypersensitivity as well as AERD pathophysiology.

An Update on Nonsteroidal Anti-Inflammatory Drug-Induced Urticaria

BACKGROUND

Hypersensitivity reactions to non-steroidal anti-inflammatory drugs (HR-NSAIDs) are common adverse events related to the widespread use of over-the-counter NSAIDs for the treatment of a variety of inflammatory conditions. Urticaria is the most commonly reported immediate cutaneous clinical sign of HR-NSAIDs, but it can be a manifestation of pathophysiologically different clinical entities that require different therapeutic strategies. The aim of this study is to ease the identification of the correct phenotype of HR-NSAIDs in patients reporting urticaria associated with the intake of NSAIDs and provide updated information about their diagnosis and management.

METHODS

The study is a narrative review conducted by collecting the most relevant and up-todate data related to the classification, pathophysiology, severity, and prognosis of NSAID hypersensitivity reactions. PubMed and Embase scientific databases were used as search engines to select relevant articles.

RESULTS

Patients developing HR-NSAIDs can be divided into two categories: selective responders (SR), who develop reactions after the administration of a single specific NSAID due to an underlying IgE or T-cell mediated hypersensitivity mechanism, or cross-intolerant (CI), who develop reactions to more than one chemically unrelated NSAIDs due to abnormalities in the biochemical pathways related with prostaglandin metabolism, independently from an underlying immunological mechanism. Five major different categories of HR-NSAIDs have been identified: NSAIDs-exacerbated cutaneous disease (NECD), NSAIDs-induced urticaria/angioedema with/without respiratory and systemic symptoms of anaphylaxis (NIUAA), and NSAIDsexacerbated respiratory disease (NERD), which are developed by CI patients, and single NSAIDs-induced urticaria, angioedema and/ or anaphylaxis (SNIUAA) and single NSAIDsinduced delayed hypersensitivity reactions (SNIDHR), which are developed by CI patients. In vivo and in vitro diagnostic tests have rarely been shown to be reliable in all these entities and therefore are not routinely used in clinical practice. The management in SR patients consists of strict avoidance of the culprit drug, while for cross-intolerance reactions oral tolerance tests with safe alternative drugs (e.g. weak COX-1 inhibitors or selective COX-2 inhibitors) can be performed.

CONCLUSION

HR-NSAIDs are being observed with increasing frequency, however, the pathogenesis behind some NSAIDS-associated clinical entities is still unclear. Diagnosis is mostly based on a thorough clinical history and confirmed by a drug challenge test. Clinical management is based on strict avoidance and use of alternative tolerated medications. Overall, all therapeutic decisions depend on the correct identification of the type of reaction the patient experienced.

Cofactors in food anaphylaxis in adults

Around 25% to 50% of food-induced allergic reactions in adults cause anaphylaxis, and epidemiologic evidence suggests that food is the most common cause of anaphylaxis. Reaction severity is unpredictable, and patients will often experience reactions of variable severity, even to an identical exposure (both dose and allergen). A common explanation for this phenomenon has been the impact of "cofactors"-factors that might contribute to reaction severity independent of the allergen exposure. Cofactors can influence reaction severity in 2 ways: either by reducing the reaction threshold (ie, the dose needed to trigger any symptoms) so that patients have no symptoms in the absence of the cofactor and only react with the cofactor present, or by increasing reaction severity such that individuals have only mild symptoms in the absence of the cofactor, but a more severe reaction when the cofactor is present. Indeed, the same patient may have reactions with different cofactors or even need more than one cofactor to develop a severe reaction. Cofactors reportedly play a role in approximately 30% of anaphylaxis reactions in adults. Exercise, nonsteroidal, anti-inflammatory drugs, alcohol, and sleep deprivation are the most frequent cofactors reported. Routine evaluation of the possible involvement of cofactors is essential in managing patients with food anaphylaxis: in patients with a suggestive history but a negative oral food challenge, cofactors should be taken into account to provide appropriate advice to reduce the risk of future anaphylaxis.

Mastocytosis presenting with mast cell‐mediator release‐associated symptoms elicited by cyclo oxygenase inhibitors: prevalence, clinical, and laboratory features

Background

Nonsteroidal anti‐inflammatory drugs (NSAIDs) are frequently avoided in mastocytosis, because of a potential increased risk for drug hypersensitivity reactions (DHRs) due to inhibition of cyclo‐oxygenase (COX), subsequent depletion of prostaglandin E₂ and release of leukotrienes.

Objectives

Here, we aimed at determining the prevalence of mast cell (MC) mediator release symptoms triggered by NSAIDs in mastocytosis patients and the associated clinical and laboratory features of the disease.

Methods

Medical records from 418 adults to 223 pediatric mastocytosis patients were retrospectively reviewed. Patients were classified according to tolerance patterns to NSAIDs and other COX inhibitors (COXi) and compared for epidemiological, clinical and laboratory findings.

Results

Overall, 87% of adults and 91% of pediatric patients tolerated NSAIDs and other COXi. Among adult and pediatric patients presenting DHRs, 5% and 0% reacted to multiple NSAIDs, 4% and 0.7% were single reactors, and 3% and 8% were single reactors with known tolerance to paracetamol but unknown tolerance to other COXi, respectively. Among adults, hypersensitivity to ≥2 drugs was more frequent among females (p = 0.009), patients with prior history of anaphylaxis to triggers other than NSAIDs or other COXi and Hymenoptera venom (p = 0.009), presence of baseline flushing (p = 0.02), baseline serum tryptase ≥48 ng/ml (p = 0.005) and multilineage KIT mutation (p = 0.02). In contrast, tolerance to NSAIDs and other COXi was more frequent among males (p = 0.02), in patients with anaphylaxis caused by Hymenoptera venom (p = 0.02), among individuals who had skin lesions due to mastocytosis (p = 0.01), and in cases that had no baseline pruritus (p = 0.006). Based on these parameters, a score model was designed to stratify mastocytosis patients who have never received NSAIDs or other COXi apart from paracetamol, according to their risk of DHR.

Conclusions

Our results suggest that despite the frequency of MC mediator related symptoms elicited by NSAIDs and other COXi apart from paracetamol is increased among mastocytosis patients versus the general population, it is lower than previously estimated and associated with unique disease features. Patients that tolerated NSAIDs and other COXi following disease onset should keep using them. In turn, adults with unknown tolerance to such drugs and a positive score should be challenged with a preferential/selective COX‐2 inhibitor, while the remaining may be challenged with ibuprofen.

Effect of TGF-β1 on eosinophils to induce cysteinyl leukotriene E4 production in aspirin-exacerbated respiratory disease

Cysteinyl leukotriene (cysLT) overproduction and eosinophil activation are hallmarks of aspirin-exacerbated respiratory disease (AERD). However, pathogenic mechanisms of AERD remain to be clarified. Here, we aimed to find the significance of transforming growth factor beta 1 (TGF-β1) in association with cysteinyl leukotriene E4 (LTE4) production, leading to eosinophil degranulation. To evaluate levels of serum TGF-β1, first cohort enrolled AERD (n = 336), ATA (n = 442) patients and healthy control subjects (HCs, n = 253). In addition, second cohort recruited AERD (n = 34) and ATA (n = 25) patients to investigate a relation between levels of serum TGF-β1 and urinary LTE4. The function of TGF-β1 in LTE4 production was further demonstrated by ex vivo (human peripheral eosinophils) or in vivo (BALB/c mice) experiment. As a result, the levels of serum TGF-β1 were significantly higher in AERD patients than in ATA patients or HCs (P = .001; respectively). Moreover, levels of serum TGF-β1 and urinary LTE4 had a positive correlation (r = 0.273, P = .037). In the presence of TGF-β1, leukotriene C4 synthase (LTC4S) expression was enhanced in peripheral eosinophils to produce LTE4, which sequentially induced eosinophil degranulation via the p38 pathway. When mice were treated with TGF-β1, significantly induced eosinophilia with increased LTE4 production in the lung tissues were noted. These findings suggest that higher levels of TGF-β1 in AERD patients may contribute to LTE4 production via enhancing LTC4S expression which induces eosinophil degranulation, accelerating airway inflammation.

Innate immune cell dysregulation drives inflammation and disease in aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) is a complex inflammatory disorder that is not generally viewed as a disease involving the adaptive immune system but instead one largely driven by the innate immune system. This article focuses on the cellular dysregulation involving 4 central cell types: eosinophils, basophils, mast cells, and innate lymphoid type 2 cells. AERD can be envisioned as involving a self-perpetuating vicious circle in which mediators produced by a differentiated activated epithelial layer, such as IL-25, IL-33, and thymic stromal lymphopoietin, engage and activate each of these innate immune cells. The activation of these innate immune cells with their production of additional cytokine/chemokine and lipid mediators leads to further recruitment and activation of these innate immune cells. More importantly, numerous mediators produced by these innate immune cells provoke the epithelium to induce further inflammation. This self-perpetuating cycle of inflammation partially explains both current interventions suggested to ameliorate AERD (eg, aspirin desensitization, leukotriene modifiers, anti-IL-5/IL-5 receptor, anti-IL-4 receptor, and anti-IgE) and invites exploration of novel targets as specific therapies for this condition (prostaglandin D₂ antagonists or cytokine antagonists [IL-25, IL-33, thymic stromal lymphopoietin]). Several of these interventions currently show promise in small retrospective analyses but now require definite clinical trials.

P2X7R in Mast Cells is a Potential Target for Salicylic Acid and Aspirin in Treatment of Inflammatory Pain

Background

Mast cells are well known for their role in inflammatory pain. P2X7 receptor (P2X7R) has attracted much attention due to its prominent role in inflammatory diseases. Salicylates are commonly used anti-inflammatory and analgesic drugs. Until now, little has been known about whether P2X7R in mast cells is involved in inflammatory pain and whether it is a potential target for salicylates.

Methods

First, the expression of P2X receptors in mouse peritoneal mast cells was detected by using RT-PCR, immunofluorescence, calcium imaging and electrophysiological technique. In addition, the functions of P2X receptors, especially P2X7R, in mast cells were studied by using QPCR, ELISA and behavioral tests. Furthermore, P2X7R was used as a target to screen for some anti-inflammatory monomers that could inhibit its activity. At last, the effect of salicylic acid (SA) and aspirin (ASA) on the activity of P2X7R was studied by using calcium imaging, electrophysiological technique, ELISA, real-time PCR, behavioral tests, immunofluorescence and molecular docking.

Results

We found that P2X1, P2X3, P2X4 and P2X7 receptors were expressed in mouse peritoneal mast cells. The functions of different P2X receptors were various. Activation of P2X7R in mouse mast cells induced the release of inflammatory mediators, such as histamine, IL-1β, and CCL3. In addition, inflammation pain induced by high concentrations of ATP could be alleviated by P2X7R blockers or mast cell defects. Interestingly, SA or ASA could reduce high concentrations of ATP-induced inward current, P2X7R upregulation, mediators release, and inflammatory pain. SA or ASA also inhibited the inward current evoked by P2X7R agonist, BZATP. Molecular docking showed that SA or ASA had affinity for the cytoplasmic GDP-binding region of P2X7R.

Conclusion

P2X7R in mast cells was involved in inflammation pain by releasing inflammatory mediators, and P2X7R might be a potential target for SA and ASA analgesia.

Aspirin exacerbated respiratory disease (AERD): molecular and cellular diagnostic & prognostic approaches

Aspirin-exacerbated respiratory disease (AERD) is characterized by immune cells dysfunction. This study aimed to investigate the molecular mechanisms involved in AERD pathogenesis. Relevant literatures were identified by a PubMed search (2005-2019) of english language papers using the terms "Aspirin-exacerbated respiratory disease", "Allergic inflammation", "molecular mechanism" and "mutation". According to the significant role of inflammation in AERD development, ILC-2 is known as the most important cell in disease progression. ILC-2 produces cytokines that induce allergic reactions and also cause lipid mediators production, which activates mast cells and basophils, ultimately. Finally, Monoclonal antibody and Aspirin desensitization in patients can be a useful treatment strategy for prevention and treatment.

Immune-Mediated Mechanisms in Cofactor-Dependent Food Allergy and Anaphylaxis: Effect of Cofactors in Basophils and Mast Cells

Cofactors may explain why in some cases food ingestion leads to anaphylaxis while in others elicits a milder reaction or tolerance. With cofactors, reactions become more severe and/or have a lower allergen threshold. Cofactors are present in up to 58% of food anaphylaxis (FAn). Exercise, NSAIDs, and alcohol are the most frequently described, although the underlying mechanisms are poorly known. Several hypotheses have suggested the influence of these cofactors on basophils and mast cells (MCs). Exercise has been suggested to enhance MC activation by increasing plasma osmolarity, redistributing blood flow, and activating adenosine and eicosanoid metabolism. NSAIDs’ cofactor effect has been related with cyclooxygenase inhibition and therefore, prostaglandin E₂ (PGE₂) production. Indeed, overexpression of adenosine receptor 3 (A₃) gene has been described in NSAID-dependent FAn; A₃ activation potentiates FcϵRI-induced MC degranulation. Finally, alcohol has been related with an increase of histamine levels by inhibition of diamino oxidase (DAO) and also with and increase of extracellular adenosine by inhibition of its uptake. However, most of these mechanisms have limited evidence, and further studies are urgently needed. In conclusion, the study of the immune-related mechanisms involved in food allergic reactions enhanced by cofactors is of the utmost interest. This knowledge will help to design both tailored treatments and prophylactic strategies that, nowadays, are non-existent.

A Challenge for Allergologist: Application of Allergy Diagnostic Methods in Mast Cell Disorders

Primary and secondary mast cell activation syndromes (MCAS) can occur in patients with mastocytosis. During the past few years our knowledge about the pathogenesis and disease-triggering mechanisms in MCAS and mastocytosis have increased substantially. Whereas mastocytosis is characterized by an accumulation of neoplastic (clonal) mast cells (MC) in various organ systems, MCAS is defined by a massive and systemic activation of these cells. Mast cells are crucial effector cells in allergic diseases, thus their elevated number and activation can cause severe anaphylactic reactions and MCAS in patients with mastocytosis. However, these cells may also degranulate spontaneously or degranulate in response to non-allergic triggers leading to clinical symptoms. In mastocytosis patients, such symptoms may lead to the diagnosis of a primary MCAS. The diagnosis of a concomitant allergy in mastocytosis patients is challenging. In these patients, a mixed form (primary and secondary) of MCAS may be diagnosed. These patients may also suffer from life-threatening anaphylactic reactions when exposed to allergens. In these cases, the possibility of severe side effects of in vivo provocations can sometimes also limit diagnostic evaluations. In the current article, we discuss the diagnosis and management of patients suffering from mastocytosis and concomitant MCAS, with special emphasis on novel diagnostic tests and management, including allergen microarrays, recombinant allergen analysis, basophil activation tests, optimal prophylaxis, and specific therapies.

Heterogeneity of lower airway inflammation in patients with NSAID-exacerbated respiratory disease

BACKGROUND

Nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (N-ERD) asthma is characterized by chronic rhinosinusitis and intolerance of aspirin and other COX1 inhibitors. Clinical data point to a heterogeneity within the N-ERD phenotype.

OBJECTIVE

Our aim was to investigate immune mediator profiles in the lower airways of patients with N-ERD.

METHODS

Levels of cytokines (determined by using Luminex assay) and eicosanoids (determined by using mass spectrometry) were measured in bronchoalveolar lavage fluid (BALF) from patients with N-ERD (n = 22), patients with NSAID-tolerant asthma (n = 21), and control subjects (n = 11). mRNA expression in BALF cells was quantified by using TaqMan low-density arrays.

RESULTS

Lower airway eosinophilia was more frequent in N-ERD (54.5%) than in NSAID-tolerant asthma (9.5% [P = .009]). The type-2 (T2) immune signature of BALF cells was more pronounced in the eosinophilic subphenotype of N-ERD. Similarly, BALF concentrations of periostin and CCL26 were significantly increased in eosinophilic N-ERD and correlated with T2 signature in BALF cells. Multiparameter analysis of BALF mediators of all patients with asthma revealed the presence of 2 immune endotypes: T2-like (with an elevated level of periostin in BALF) and non-T2/proinflammatory (with higher levels of matrix metalloproteinases and inflammatory cytokines). Patients with N-ERD were classified mostly as having the T2 endotype (68%). Changes in eicosanoid profile (eg, increased leukotriene E₄ level) were limited to patients with N-ERD with airway eosinophilia. Blood eosinophilia appeared to be a useful predictor of airway T2 signature (area under the curve [AUC] = 0.83); however, surrogate biomarkers had moderate performance in distinguishing eosinophilic N-ERD (for blood eosinophils, AUC = 0.72; for periostin, AUC = 0.75).

CONCLUSIONS

Lower airway immune profiles show considerable heterogeneity of N-ERD, with skewing toward T2 response and eosinophilic inflammation. Increased production of leukotriene E₄ was restricted to a subgroup of patients with eosinophilia in the lower airway.

AERD Associated Nasal Polyposis: Efficacy of Postoperative Antileukotriene Therapy in Comparison with Aspirin Desensitization. A Retrospective Study

INTRODUCTION

AERD (aspirin-exacerbated respiratory disease) is a severe form of an inflammatory disease of the upper airway system. Therapy remains challenging due to a complex underlying pathophysiology.

OBJECTIVE

To evaluate the efficacy of postoperative antileukotriene therapy concerning recurrence of nasal polyposis in patients with AERD and to compare it with AD (aspirin desensitization) over time.

METHODS

In this retrospective study we analyzed AERD patients (N = 61) after functional endoscopic sinus surgery (FESS). Patients were treated at our institution postoperatively with topical mometasone (control group, N = 22), leukotriene-receptor-antagonists (montelukast [MT], N = 18) or underwent an aspirin desensitization (N = 21). Subjective parameters as assessed by SNOT (sinonasal outcome test) questionnaire and endoscopic endonasal examination (polyposis grading) were evaluated throughout a follow-up period of 6-9 and >12 (long-term) months after surgery.

RESULTS

Endoscopic endonasal examinations 6-9 months after sinus surgery showed a good disease control in all 3 groups with significant reduction in polyp grading in the AD group. After a follow-up period of more than 12 months, MT and AD patients had significantly less polyp recurrences as compared to the topical treatment group. Subjective sinonasal symptoms revealed that hyposmia and nasal obstruction were prominent factors in all 3 groups throughout the follow-up period. MT group showed significant improvement in sinonasal symptoms over time.

CONCLUSION

Postoperative treatment with leukotriene-receptor-antagonists and aspirin desensitization both significantly reduce nasal polyp recurrence. MT has a positive effect on subjective sinonasal outcomes and patients' quality of life over time.

Update on the Management of Nonsteroidal Anti-Inflammatory Drug Hypersensitivity

The clinical phenotypes of nonsteroidal anti-inflammatory drug (NSAID) hypersensitivity are heterogeneous with various presentations including time of symptom onset, organ involvements, and underlying pathophysiology. Having a correct diagnosis can be challenging. Understanding their respective mechanisms as well as developing a comprehensive classification and diagnostic algorithm are pivotal for appropriate management strategy. Treatment modalities are based on the subtypes and severity of hypersensitivity reactions. Insights into the phenotypes and endotypes of hypersensitivity reactions enable personalized management in patients with suboptimal control of disease. This review updated the recent evidence of pathophysiology, classification, diagnostic algorithm, and management of NSAID hypersensitivity reactions.

Leukotriene A4 Hydrolase Activation and Leukotriene B4 Production by Eosinophils in Severe Asthma

Asthma is associated with the overproduction of leukotrienes (LTs), including LTB4. Patients with severe asthma can be highly responsive to 5-lipoxygenase (5-LO) inhibition, which blocks production of both the cysteinyl LTs and LTB4. Production of LTB4 has traditionally been ascribed to neutrophils, mononuclear phagocytes, and epithelial cells, and acts as a chemoattractant for inflammatory cells associated with asthma. The source of LTB4 is unclear, especially in eosinophilic asthma. We speculated that the benefit of 5-LO inhibition could be mediated in part by inhibition of eosinophil-derived LTB4. LTB4 concentrations were assayed in BAL fluid from patients with severe asthma characterized by isolated neutrophilic, eosinophilic, and paucigranulocytic inflammation. Expression of LTA4 hydrolase (LTA4H) by airway eosinophils was determined by immunohistochemistry (IHC). Subsequently, peripheral blood eosinophils were activated and secreted LTB4 was quantified by enzyme immunoassay. Blood eosinophil LTA4H expression was determined by flow cytometry, qPCR, and IHC. LTB4 concentrations were elevated in BAL fluid from patients with severe asthma, including those with isolated eosinophilic inflammation, and these eosinophils displayed LTA4H via IHC. LTA4H expression by blood eosinophils was confirmed by flow cytometry, IHC, and qPCR. Robust LTB4 production by blood eosinophils was observed in response to some, but not all, stimuli. We demonstrated that eosinophils express LTA4H transcripts and protein, and can be stimulated to secrete LTB4. We speculate that in many patients with asthma, eosinophil-derived LTB4 is increased, and this may contribute to the efficacy of 5-LO inhibition.

The time course of nasal cytokine secretion in patients with aspirin-exacerbated respiratory disease (AERD) undergoing aspirin desensitization: preliminary data

PURPOSE

Aspirin-exacerbated respiratory disease (AERD) is a severe form of chronic rhinosinusitis with nasal polyps (CRSwNP) accompanied by asthma and an aspirin intolerance. The underlying pathomechanism of AERD still remains unclear, recent data suggest a complex inflammatory imbalance. In the present study, we investigated the cytokine patterns in AERD, CRSwNP and healthy control patients. Furthermore, we describe the change in cytokine level in the course of aspirin desensitization (AD) with continuous intake of aspirin.

METHODS

The study included a total of 104 participants, 48 healthy controls, 45 patients with nasal polyps and 11 patients with AERD undergoing AD. Nasal secretions were analyzed for IL-1β, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17, THF-α, IFN-γ, eotaxin and ECP using Bio-Plex Human Cytokine Assay and Uni-CAP FEIA. Baseline measurements of cytokine levels were performed in all 104 patients; in patients with AERD, follow-up was performed 1-6 and 6-24 months after the initiation of AD.

RESULTS

Our preliminary results show a T_H2 dominated, eosinophilic milieu in AERD patients, which decreased in the first weeks of AD. However, after 6 months of AD, proinflammatory cytokines show a tendency to increase again. Also, T_H1 as well as T_reg associated cytokine seem to increase over time.

CONCLUSIONS

For the first time, the present work shows the cytokine pattern in nasal secretions of AERD patients before and during AD. Further investigation of the complex interaction of inflammatory cytokines during AD might reveal important insights into the disease entity of AERD and open up new horizons for a targeted therapy.

Suppression of aspirin-mediated eosinophil activation by prostaglandin E2: Relevance to aspirin and nonsteroidal anti-inflammatory drug hypersensitivity

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is characterized by severe, sometimes life-threatening reactions to nonsteroidal anti-inflammatory drugs (NSAIDs). Mechanisms driving the disease include overproduction of leukotrienes and loss of anti-inflammatory prostaglandin E₂ (PGE₂) production. Many cell types contribute to the disease; however, eosinophils are markedly elevated and are important drivers of pathologic findings.

OBJECTIVE

To investigate the capacity of aspirin and NSAIDs to drive eosinophil activation and the ability of PGE₂ to inhibit this activation.

METHODS

Eosinophils were purified from blood of healthy individuals without AERD and stimulated with lysine aspirin, ketorolac, or sodium salicylate. The role of PGE₂ in altering activation was determined by incubating eosinophils with increasing doses of PGE₂ before lysine aspirin stimulation. Specific PGE₂ receptor use was determined by incubating eosinophils with receptor agonists and antagonists before aspirin stimulation. Cysteinyl leukotrienes (CysLTs), leukotriene B₄ (LTB₄), and eosinophil-derived neurotoxin (EDN) were quantified by enzyme-linked immunosorbent assay.

RESULTS

Stimulation of eosinophils with lysine aspirin, ketorolac, or sodium salicylate resulted in secretion of CysLTs and LTB₄ in the absence of EDN release. Low doses of PGE₂ inhibited LTB₄ and CysLT release, an effect lost at higher PGE₂ concentrations. Use of butaprost, an EP₂ receptor agonist, suppressed lysine aspirin stimulation. This mechanism was supported by blocking activity of the EP₁ and EP₃ receptors.

CONCLUSION

Eosinophils can be directly activated by NSAIDs via cyclooxygenase-independent pathways to produce CysLTs and LTB₄. This effect can be inhibited by PGE₂ acting through the EP₂ receptor. The recognized loss of EP₂ receptor expression combined with low PGE₂ levels explains in part the sensitivity to NSAIDs.

NSAID-induced reactions: classification, prevalence, impact, and management strategies

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the leading cause of hypersensitivity drug reactions. The different chemical structures, cyclooxygenase 1 (COX-1) and/or COX-2 inhibitors, are taken at all ages and some can be easily obtained over the counter. Vasoactive inflammatory mediators like histamine and leukotriene metabolites can produce local/systemic effects. Responders can be selective (SR), IgE or T-cell mediated, or cross-intolerant (CI). Inhibition of the COX pathway is the common mechanism in CI, with the skin being the most frequent organ involved, followed by the lung and/or the nose. An important number of cases have skin and respiratory involvement, with systemic manifestations ranging from mild to severe anaphylaxis. Among SR, this is the most frequent entity, often being severe. Recent years have seen an increase in reactions involving the skin, with many cases having urticaria and/or angioedema in the absence of chronic urticaria. Aspirin, the classical drug involved, has now been replaced by other NSAIDs, with ibuprofen being the universal culprit. For CI, no in vivo/in vitro diagnostic methods exist and controlled administration is the only option unless the cases evaluated report repetitive and consistent episodes with different NSAIDs. In SR, skin testing (patch and intradermal) with 24-48 reading can be useful, mainly for delayed T-cell responses. Acetyl salicylic acid (ASA) is the test drug to establish the diagnosis and confirm/exclude CI by controlled administration. Desensitization to ASA has been extensively used in respiratory cases though it can also be applied in those cases where it is required.

[NSAID urticaria: Similar management to acute urticaria]

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most common providers of immediate hypersensitivity reactions. Among these reactions, isolated acute urticaria is the most common clinical feature with a non-allergic origin. It is a pharmacological side effect resulting from the alteration of arachidonic acid metabolism induced by NSAIDs. Diagnosis of this acute urticaria is clinical, requiring no allergy testing. Currently, the recommended therapeutic management of NSAID urticaria is the avoidance of all NSAID with COX-1 inhibitor activity (even if when reintroduced, they are most often well tolerated) and the use of selective COX-2 inhibitors. This review focuses on urticaria reactions to NSAIDs, which are simple to manage.

Effect of rapid desensitization on platelet inhibition and basophil activation in patients with aspirin hypersensitivity and coronary disease

Aims

To determine antiplatelet efficacy after desensitization in patients with a history of aspirin hypersensitivity.

Methods and results

We conducted a case-control study to evaluate the efficacy of aspirin 1 day (D1) and 6-8 weeks (W6-8) after desensitization. We also assessed ex vivo basophil reactivity to aspirin after desensitization. Cases were patients with coronary artery disease (CAD) and documented history of aspirin hypersensitivity who underwent rapid successful oral desensitization to aspirin. Controls were patients with stable CAD without hypersensitivity and receiving aspirin. Among 56 cases, 27 received aspirin for acute coronary syndromes and 29 were treated for stable CAD. Aspirin was effective (defined as light transmission aggregometry induced by arachidonic acid ≤20%) at D1 in 86% of cases (P = 0.045 vs. controls) and in 95% at W6-8, vs. 100% of controls (P = 0.39). Urinary excretion of thromboxane B2 diminished substantially in cases (P < 0.0001, D0 vs. W6-8) but remained higher than in controls (P = 0.03). Platelet reactivity (defined by platelet P-selectin expression, activated glycoprotein IIb/IIIa inhibitors, and platelet-monocyte aggregates) was similar in cases between D0 and D1 but decreased at W6-8. Basophil activation (quantified by upregulation of CD203c in response to aspirin) was higher in cases at W6-8 than in controls (P = 0.0002).

Conclusion

Thus, following rapid desensitization, aspirin achieves rapid biological efficacy, which is slightly lower at D1, but becomes indistinguishable from chronically treated patients at W6-8. Persistent basophil activation several weeks after desensitization suggests infraclinical hypersensitivity and the need to continue aspirin to maintain desensitization.

Alcohol-induced respiratory symptoms improve after aspirin desensitization in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is characterized by chronic eosinophilic rhinosinusitis, nasal polyps, asthma, and respiratory sensitivity to aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs). In addition to sensitivity to aspirin and NSAIDs, the majority of patients with AERD have been reported to have respiratory intolerance associated with the consumption of alcohol.

METHODS

A multicenter prospective cohort study was performed. Patients with AERD confirmed by aspirin challenge were eligible to participate. Those who described themselves as able to tolerate alcohol consumption were excluded. Patients underwent aspirin desensitization following endoscopic sinus surgery. A questionnaire was distributed to patients before and after desensitization to determine pre-desensitization and post-desensitization symptoms associated with alcohol ingestion.

RESULTS

Forty-five patients were enrolled and 37 patients completed the study. The most common pre-desensitization symptoms were nasal congestion (95.6%), rhinorrhea (46.7%), and wheezing (40%). Improvement in the ability to tolerate alcohol was noted in 86.5% of participants (95% confidence interval [CI], 75.5% to 97.5%) and 70.3% of participants (95% CI, 55.5% to 85.0%) described desensitization to be "very helpful" or "extremely helpful" for their ability to tolerate alcohol.

CONCLUSION

The majority of patients with AERD who experience respiratory symptoms with alcohol consumption describe improvement in this domain following aspirin desensitization.

Aspirin exacerbated respiratory disease: Current topics and trends

Aspirin-exacerbated respiratory disease is a chronic and treatment-resistant disease, characterized by the presence of eosinophilic rhinosinusitis, nasal polyposis, bronchial asthma, and nonsteroidal anti-inflammatory drugs hypersensitivity. Alterations in arachidonic acid metabolism may induce an imbalance between pro-inflammatory and anti-inflammatory substances, expressed as an overproduction of cysteinyl leukotrienes and an underproduction of prostaglandin E2. Although eosinophils play a key role, recent studies have shown the importance of other cells and molecules in the development of the disease like mast cells, basophils, lymphocytes, platelets, neutrophils, macrophages, epithelial respiratory cells, IL-33 and thymic stromal lymphopoietin, making each of them promissory diagnostic and treatment targets. In this review, we summarize the most important clinical aspects of the disease, including the current topics about diagnosis and treatment, like provocation challenges and aspirin desensitization. We also discuss recent findings in the pathogenesis of the disease, as well as future trends in diagnosis and treatment, including monoclonal antibodies and a low salicylate diet as a treatment option.

Aspirin and Nonsteroidal Antiinflammatory Drugs Hypersensitivity and Management

Aspirin and nonsteroidal antiinflammatory drugs (NSAIDs) are widely used in the United States and throughout the world for a variety of indications. Several unique hypersensitivity syndromes exist to this class of medications, making them one of the common reasons for consultation to the allergist. The lack of any laboratory-based diagnostic studies to assist in identifying the culprits in these reactions make evaluation of aspirin and NSAID hypersensitivity challenging. Identifying patients appropriate for oral challenge and/or desensitization protocols is the standard pragmatic approach to this issue when it arises.

Prostaglandins and Their Receptors in Eosinophil Function and As Therapeutic Targets

Of the known prostanoid receptors, human eosinophils express the prostaglandin D₂ (PGD₂) receptors DP1 [also D-type prostanoid (DP)] and DP2 (also chemoattractant receptor homologous molecule, expressed on Th2 cells), the prostaglandin E₂ receptors EP2 and EP4, and the prostacyclin (PGI₂) receptor IP. Prostanoids can bind to either one or multiple receptors, characteristically have a short half-life in vivo, and are quickly degraded into metabolites with altered affinity and specificity for a given receptor subtype. Prostanoid receptors signal mainly through G proteins and naturally activate signal transduction pathways according to the G protein subtype that they preferentially interact with. This can lead to the activation of sometimes opposing signaling pathways. In addition, prostanoid signaling is often cell-type specific and also the combination of expressed receptors can influence the outcome of the prostanoid impulse. Accordingly, it is assumed that eosinophils and their (patho-)physiological functions are governed by a sensitive prostanoid signaling network. In this review, we specifically focus on the functions of PGD₂, PGE₂, and PGI₂ and their receptors on eosinophils. We discuss their significance in allergic and non-allergic diseases and summarize potential targets for drug intervention.

Mast cells in asthma--state of the art

Mast cells (MCs) play a central role in tissue homoeostasis, sensing the local environment through numerous innate cell surface receptors. This enables them to respond rapidly to perceived tissue insults with a view to initiating a co-ordinated programme of inflammation and repair. However, when the tissue insult is chronic, the ongoing release of multiple pro-inflammatory mediators, proteases, cytokines and chemokines leads to tissue damage and remodelling. In asthma, there is strong evidence of ongoing MC activation, and their mediators and cell-cell signals are capable of regulating many facets of asthma pathophysiology. This article reviews the evidence behind this.

Eosinophils and Mast Cells in Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) involves overexpression of proinflammatory mediators, including 5-lipoxygenase and leukotriene C₄ synthase (LTC₄S), resulting in constitutive overproduction of cysteinyl leukotrienes. Mast cells and eosinophils have roles in mediating many of the observed effects. Increased levels of both interleukin-4 (IL-4) and interferon (IFN)-γ are present in the tissue of patients with AERD. Previous studies showed that IL-4 is primarily responsible for the upregulation of LTC₄S by mast cells. Our studies show that IFN-γ, but not IL-4, drives this process in eosinophils. This article examines the overall role that eosinophils and mast cells contribute to the pathophysiology of AERD.

Eicosanoid Mediators in the Airway Inflammation of Asthmatic Patients: What is New?

Lipid mediators contribute to inflammation providing both pro-inflammatory signals and terminating the inflammatory process by activation of macrophages. Among the most significant biologically lipid mediators, these are produced by free-radical or enzymatic oxygenation of arachidonic acid named "eicosanoids". There were some novel eicosanoids identified within the last decade, and many of them are measurable in clinical samples by affordable chromatography-mass spectrometry equipment or sensitive immunoassays. In this review, we present some recent advances in understanding of the signaling by eicosanoid mediators during asthmatic airway inflammation. Eicosanoid profiling in the exhaled breath condensate, induced sputum, or their metabolites measurements in urine is complementary to the cellular phenotyping of asthmatic inflammation. Special attention is paid to aspirin-exacerbated respiratory disease, a phenotype of asthma manifested by the most profound changes in the profile of eicosanoids produced. A hallmark of this type of asthma with hypersensitivity to non-steroid anti-inflammatory drugs (NSAIDs) is to increase biosynthesis of cysteinyl leukotrienes on the systemic level. It depends on transcellular biosynthesis of leukotriene C₄ by platelets that adhere to granulocytes releasing leukotriene A₄. However, other abnormalities are also reported in this type of asthma as a resistance to anti-inflammatory activity of prostaglandin E₂ or a robust eosinophil interferon-γ response resulting in cysteinyl leukotrienes production. A novel mechanism is also discussed in which an isoprostane structurally related to prostaglandin E₂ is released into exhaled breath condensate during a provoked asthmatic attack. However, it is concluded that any single eicosanoid or even their complex profile can hardly provide a thorough explanation for the mechanism of asthmatic inflammation.

Emerging concepts: mast cell involvement in allergic diseases

In a process known as overt degranulation, mast cells can release all at once a diverse array of products that are preformed and present within cytoplasmic granules. This occurs typically within seconds of stimulation by environmental factors and allergens. These potent, preformed mediators (ie, histamine, heparin, serotonin, and serine proteases) are responsible for the acute symptoms experienced in allergic conditions such as allergic conjunctivitis, allergic rhinitis, allergy-induced asthma, urticaria, and anaphylaxis. Yet, there is reason to believe that the actions of mast cells are important when they are not degranulating. Mast cells release preformed mediators and inflammatory cytokines for periods after degranulation and even without degranulating at all. Mast cells are consistently seen at sites of chronic inflammation, including nonallergic inflammation, where they have the ability to temper inflammatory processes and shape tissue morphology. Mast cells can trigger actions and chemotaxis in other important immune cells (eg, eosinophils and the newly discovered type 2 innate lymphocytes) that then make their own contributions to inflammation and disease. In this review, we will discuss the many known and theorized contributions of mast cells to allergic diseases, focusing on several prototypical allergic respiratory and skin conditions: asthma, chronic rhinosinusitis, aspirin-exacerbated respiratory disease, allergic conjunctivitis, atopic dermatitis, and some of the more common medication hypersensitivity reactions. We discuss traditionally accepted roles that mast cells play in the pathogenesis of each of these conditions, but we also delve into new areas of discovery and research that challenge traditionally accepted paradigms.

Eosinophil production of prostaglandin D2 in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) differs from aspirin-tolerant disease in part because of eosinophilic tissue infiltration and overexpression of arachidonic acid metabolic pathway components that lead to enhanced secretion of cysteinyl leukotrienes and prostaglandin (PG) D₂ observed constitutively and paradoxically in response to aspirin and other COX inhibitors. We have previously demonstrated the capacity of IFN-γ to drive cysteinyl leukotriene expression and response.

OBJECTIVE

We investigated eosinophils as a source of PGD₂ production in patients with AERD.

METHODS

Eosinophils were enriched from tissue and peripheral blood obtained from control subjects, patients with aspirin-tolerant disease, and patients with AERD. mRNA was extracted and evaluated for expression of hematopoietic prostaglandin D synthase (hPGDS). Expression of hPGDS protein was confirmed with Western hybridization and immunofluorescence staining. Cells were stimulated with aspirin, and secretion of PGD₂ was quantified. CD34⁺ progenitor cells were isolated and matured into eosinophils in the presence or absence of IFN-γ and hPGDS mRNA, and PGD₂ release was measured.

RESULTS

Gene expression analysis revealed that eosinophils from tissue and blood of patients with AERD display increased levels of hPGDS compared with asthmatic and control samples. Western hybridization confirmed the increase in hPGDS mRNA translated to increased protein expression. Immunofluorescence confirmed mast cells and eosinophils from tissue of patients with AERD and asthma demonstrated hPGDS expression, with higher levels in eosinophils from patients with AERD. Incubation of eosinophils from blood and tissue with aspirin stimulated PGD₂ release. IFN-γ-matured eosinophil progenitors showed enhanced hPGDS expression and increased levels of PGD₂ release at baseline and after aspirin stimulation.

CONCLUSIONS

In addition to mast cells, eosinophils represent an important source of PGD₂ in patients with AERD and identify a new target for therapeutic intervention.

Loki zupa (Luooukezupa) decoction reduced airway inflammation in an OVA-induced asthma mouse model

Background

Loki zupa (Luooukezupa) decoction, consisting of the roots of Hyssopuscuspidatus Boriss (Shenxiangcao) and Irishalophila Pall root (Yuanweigen), is commonly used in Uygur medicine to treat asthma. However, the mode of action of this material has yet to be elucidated. This study aims to investigate the effects of Loki zupa decoction on the airway inflammation of an ovalbumin (OVA)-induced asthma mouse model.

Methods

Mice were divided into normal control (NC), asthma (A), high, medium and low doses of Loki zupa decoction (L 14.0, L 7.0, L 3.5), water extract (LW), n-butanol extract (LN), ethyl acetate extract (LE) and dexamethasone (DEX) groups. Antiasthmatic model was induced by OVA sensitization and challenged using BALB/c mice. Airway hyperresponsiveness (AHR) toward methacholine (Mch) was assessed using Buxco equipment. Lung inflammation was measured by hematoxylin and eosin staining and bronchoalveolar lavage fluid (BALF) cell count and classification. Inflammatory cytokines in BALF and serum were analyzed by Bio-Plex assay, and mRNA levels were investigated by qPCR analysis. The roots of H. Boriss (250 g) and I. Pall (250 g) were decocted, concentrated and diluted to 14.0, 7.0 and 3.5 g crude herb/kg body weight. The LW, LN and LE of the Loki zupa decoction were prepared and diluted to a dose equivalent to 7 g of crude herb/kg body weight.

Results

Loki zupa decoction and its extracts significantly attenuated the AHR towards Mch (all P < 0.05). Treatment with Loki zupa decoction and its extracts relieved the infiltration of inflammatory cells in and around the airways, and reduced the total white blood cell (all P < 0.05), neutrophil (all P < 0.05), monocyte (all P < 0.05) and eosinophil (all P < 0.05) counts in the BALF. The BALF samples collected from the mice treated with the Loki zupa decoction and its extracts had lower levels of IL-1β (all P < 0.05), TNF-α (all P < 0.05), IL-2 (all P < 0.05), IL-4 (P = 0.047) and IL-5 (all P < 0.05). The serum samples of these mice also had lower IL-1β (all P < 0.05), TNF-α (all P < 0.05), IL-4 (all P < 0.05) and IL-5 (all P < 0.05) levels and higher levels of IFN-γ (P < 0.001) compared with the OVA-induced asthma mouse model. qPCR analysis revealed that Loki zupa decoction and its extracts inhibited mRNA expression of IL-4 (all P < 0.05), IL-5 (all P < 0.05) and IL-13 (all P < 0.05) and promoted mRNA expression of IFN-γ (all P < 0.05) in asthmatic mice.

Conclusion

Loki zupa decoction reduced AHR, attenuated airway inflammation, promoted Th1 and suppressed Th2 cell functions in an OVA-induced asthma mouse model.

Electronic supplementary material

The online version of this article (doi:10.1186/s13020-016-0094-9) contains supplementary material, which is available to authorized users.

Role of Prostaglandin D2 and DP1 Receptor on Japanese Cedar Pollen-Induced Allergic Rhinitis in Mice

Although we previously demonstrated the contribution of the DP1receptor in nasal obstruction using animals sensitized with ovalbumin in the presence of adjuvant, the contribution of the DP1receptor in sneezing is unclear. Here, we developed a mouse model of Japanese cedar (JC:Cryptomeria japonica) pollinosis to evaluate the symptoms of sneezing. To achieve this, we used JC pollen crude extract in the absence of adjuvant to sensitize mice to develop a model closer to the pathophysiology of human JC pollinosis. The immunologic and pharmacologic features of this model are highly similar to those observed in JC pollinosis in humans. Using this model, we found that DP1receptor antagonists suppressed JC pollen extract-induced sneezing and that a DP1receptor agonist induced sneezing. Moreover, JC pollen extract-induced sneezing was diminished in DP1receptor knockout mice. In conclusion, we developed a novel mouse model of allergic rhinitis that closely mimics human JC pollinosis. A strong contribution of DP1receptor signaling to sneezing was demonstrated using this model, suggesting that DP1receptor antagonists could suppress sneezing and nasal obstruction, and therefore these agents could be a new therapeutic option for allergic rhinitis.

Aspirin-Exacerbated Diseases: Advances in Asthma with Nasal Polyposis, Urticaria, Angioedema, and Anaphylaxis

Aspirin-exacerbated diseases are important examples of drug hypersensitivities and include aspirin-exacerbated respiratory disease (AERD), aspirin- or non-steroidal anti-inflammatory drug (NSAID)-induced urticaria/angioedema, and aspirin- or NSAID-induced anaphylaxis. While each disease subtype may be distinguished by unique clinical features, the underlying mechanisms that contribute to these phenotypes are not fully understood. However, the inhibition of the cyclooxygenase-1 enzyme is thought to play a significant role. Additionally, eosinophils, mast cells, and their products, prostaglandins and leukotrienes, have been identified in the pathogenesis of AERD. Current diagnostic and treatment strategies for aspirin-exacerbated diseases remain limited, and continued research focusing on each of the unique hypersensitivity reactions to aspirin is essential. This will not only advance the understanding of these disease processes, but also lead to the subsequent development of novel therapeutics that patients who suffer from aspirin-induced reactions desperately need.

Nonsteroidal anti-inflammatory-induced inhibition of signal transducer and activator of transcription 6 (STAT-6) phosphorylation in aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin desensitization provides long-term clinical benefits. The exact mechanisms of aspirin desensitization are not clearly understood.

OBJECTIVE

We sought to evaluate the effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on T-cell activation of the IL-4 pathway in aspirin-sensitive patients with asthma and control subjects.

METHODS

A total of 11 aspirin-sensitive patients with asthma, 10 aspirin-tolerant patients with asthma, and 10 controls without asthma were studied. PBMCs were stimulated with an anti-CD3 antibody and IL-4 or IL-12, with and without the presence of NSAIDs. The expression of phosphorylated signal transducers and activators of transcription 6 (pSTAT6), phosphorylated signal transducers and activators of transcription 4, and IL-4 was detected in CD4 T cells by flow cytometry.

RESULTS

Stimulation with a combination of anti-CD3 and IL-4 induced pSTAT6 in CD4 T cells from all subjects. The induction of pSTAT6 was significantly higher in aspirin-sensitive patients with asthma than in controls subjects. The increase in pSTAT6 was inhibited in a dose-dependent manner by aspirin and indomethacin and minimally by sodium salicylate. This inhibition was strongest in aspirin-sensitive patients. Two-group comparisons showed significant differences in pSTAT6 inhibition by all concentrations of indomethacin and aspirin: between aspirin-sensitive and aspirin-tolerant groups and between aspirin-sensitive and control groups. No differences were found between aspirin-tolerant and control groups at all 3 concentrations. The inhibition of pSTAT6 was associated with reduced IL-4 expression.

CONCLUSIONS

NSAIDs inhibited signal transducers and activators of transcription 6 signaling in CD4 T cells. This inhibition was significantly higher in aspirin-sensitive patients than in aspirin-tolerant subjects and was associated with reduced expression of IL-4. These findings have implications for clinical benefits of aspirin desensitization in aspirin-sensitive patients with asthma.

Association of TRPM3 Polymorphism (rs10780946) and Aspirin-Exacerbated Respiratory Disease (AERD)

INTRODUCTION

Aspirin-exacerbated respiratory disease (AERD) refers to the combination of asthma rhinosinusitis and poliposis; ingestion of aspirin or other non-steroid anti-inflammatory drugs exacerbate asthma-like symptoms. The pathogenesis of AERD is unknown, and genetic and environmental factors contribute to the disease. Our objective is identifying polymorphisms associated with susceptibility in a Mexican mestizo population.

METHODS

Primarily we performed custom Illumina goldengate array-based genotyping of 1512 SNPs, carefully selected from a variety of acute/chronic inflammatory lung conditions previously reported. Four SNPs in TRPM3 gene showed the lowest p-values (rs10780946, rs7025694, rs1889915, and rs7047645). We further selected rs10780946 and rs7025694 for validation using Taqman genotyping (n = 743; 288 AERD, 272 ATA, and 183 HC).

RESULTS

rs10780946 showed association when compared between AERD and ATA groups under co-dominant (p = 0.006), dominant (p = 0.002), overdominant (p = 0.01), and log-additive (p = 0.03) genetic models. AERD showed increased heterozygous TC (rs10780946-rs7025694) haplotype compared to ATA and HC (p < 0.05). We could not confirm any association between rs7025694 and AERD.

CONCLUSION

rs10780946 TRPM3 polymorphism is associated with AERD susceptibility.

Utility of low-dose oral aspirin challenges for diagnosis of aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is diagnosed through graded aspirin challenges that induce hypersensitivity reactions and eicosanoid level changes. It is not known whether diagnostically useful changes also occur after low-dose aspirin challenges that do not induce hypersensitivity reactions.

OBJECTIVE

To investigate the utility of low-dose oral aspirin challenges for diagnosing AERD by measuring different clinical parameters and eicosanoid changes.

METHODS

Sixteen patients with AERD and 13 patients with aspirin-tolerant asthma underwent oral challenges with low-dose (20 or 40 mg) aspirin and diagnostic oral graded aspirin challenges (up to 325 mg of aspirin). Forced expiratory volume in 1 second, nasal peak flow, the fraction of exhaled nitric oxide (FeNO), and eicosanoid levels in plasma and urine were analyzed.

RESULTS

In patients with AERD but not in those with aspirin-tolerant asthma, 40-mg aspirin challenges induced a significant mean (SEM) decrease from baseline in FeNO (19% [5.1%]; P = .001) without causing any hypersensitivity reaction. The FeNO decrease also occurred after higher-dose aspirin challenges (27.8% [4.9%]; P < .001). The sensitivity and specificity of 40-mg aspirin-induced FeNO changes for identifying AERD were 90% and 100% with an area under the curve of 0.98 (95% CI, 0.92-1.00). The low-dose challenge also induced a significant leukotriene E4 urine increase in patients with AERD (from 6.32 [0.08] to 6.91 [0.15] log-pg/mg creatinine; P < .001), but the sensitivity and specificity of these changes were less than for the FeNO changes.

CONCLUSION

The low-dose aspirin-induced decrease in FeNO in patients with AERD may be useful for the diagnosis of aspirin allergy without inducing a hypersensitivity reaction.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01320072.

Aspirin induces IL-4 production: augmented IL-4 production in aspirin-exacerbated respiratory disease

Aspirin hypersensitivity is a hallmark of aspirin-exacerbated respiratory disease (AERD), a clinical syndrome characterized by the severe inflammation of the respiratory tract after ingestion of cyclooxygenase-1 inhibitors. We investigated the capacity of aspirin to induce interleukin-4 (IL-4) production in inflammatory cells relevant to AERD pathogenesis and examined the associated biochemical and molecular pathways. We also compared IL-4 production in peripheral blood mononuclear cells (PBMCs) from patients with AERD vs aspirin-tolerant asthma (ATA) upon exposure to aspirin. Aspirin induced IL-4 expression and activated the IL-4 promoter in a report assay. The capacity of aspirin to induce IL-4 expression correlated with its activity to activate mitogen-activated protein kinases, to form DNA-protein complexes on P elements in the IL-4 promoter and to synthesize nuclear factor of activated T cells, critical transcription factors for IL-4 transcription. Of clinical importance, aspirin upregulated IL-4 production twice as much in PBMCs from patients with AERD compared with PBMCs from patients with ATA. Our results suggest that IL-4 is an inflammatory component mediating intolerance reactions to aspirin, and thus is crucial for AERD pathogenesis.

The whole-genome expression analysis of peripheral blood mononuclear cells from aspirin sensitive asthmatics versus aspirin tolerant patients and healthy donors after in vitro aspirin challenge

Background

Up to 30 % of adults with severe asthma are hypersensitive to aspirin and no unambiguous theory exists which provides a satisfactory explanation for the occurrence of aspirin-induced asthma (AIA) in some asthmatic patients. Therefore, the aim of this study was to compare the AIA expression profile against aspirin tolerant asthma (ATA) and healthy volunteers (HV) profile in peripheral blood mononuclear cells (PBMCs) after in vitro aspirin challenge in Caucasian population.

Methods

PBMCs were separated from blood of three groups of subjects - 11 AIA, 7 ATA and 15 HV and then stimulated by either 2 μM lysine aspirin or 20 μM lysine as a control. Subsequently, RNA was isolated, transcribed into cDNA and subjected to microarray and qPCR studies. Simultaneously, protein was extracted from PBMCs and used in further immunoblotting analysis.

Results

The validation of results at mRNA level has shown only three genes, whose expression was significantly altered between comprising groups. mRNA expression of CNPY3 in PBMCs in AIA was significantly lower (-0.41 ± 2.67) than in HV (1.04 ± 2.69), (p = 0.02); mRNA expression of FOSL1 in PBMCs in AIA was also significantly decreased (-0.66 ± 2.97) as opposed to HV (0.31 ± 4.83), (p = 0.02). While mRNA expression of ERAS in PBMCs was increased (1.15 ± 0.23) in AIA in comparison to HV (-1.32 ± 0.41), (p = 0.03). At protein level the changed expression of one protein was confirmed. Protein expression of FOSL1 in PBMCs in AIA was both significantly lower (-0.86 ± 0.08) than in ATA (0.39 ± 0.42), (p = 0.046) and in HV (0.9 ± 0.27), (p = 0.007).

Conclusions

This pilot study implies a positive association between CNPY3, ERAS, FOSL1 and aspirin-intolerant asthma, suggesting that these findings would be useful for further investigations of NSAIDs mechanism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0305-4) contains supplementary material, which is available to authorized users.

Factors driving the aspirin exacerbated respiratory disease phenotype

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is explained in part by overexpression of 5-lipoxygenase and leukotriene C4 synthase (LTC4S), resulting in constitutive overproduction of cysteinyl leukotrienes (CysLTs) and driving the surge in CysLT production that occurs with aspirin ingestion. Similarly, AERD is characterized by the overexpression of CysLT receptors. Increased levels of both interleukin (IL)-4 and interferon (IFN)-γ are present in the tissue of AERD subjects. Previous studies demonstrated that IL-4 is primarily responsible for the up-regulation of LTC4S by mast cells.

METHODS

Literature review.

RESULTS

Our previous studies demonstrated that IFN-γ, but not IL-4, drives this process in eosinophils. These published studies also extend to both IL-4 and IFN-γ the ability to up-regulate CysLT receptors. Prostaglandin E2 (PGE2) acts to prevent CysLT secretion by inhibiting mast cell and eosinophil activation. PGE2 concentrations are reduced in AERD, and our published studies confirm that this reflects diminished expression of cyclooxygenase (COX)-2. A process again that is driven by IL-4. Thus, IL-4 and IFN-γ together play an important pathogenic role in generating the phenotype of AERD. Finally, induction of LTC4S and CysLT1 receptors by IL-4 reflects in part the IL-4-mediated activation of signal transducer and activator of transcription 6 (STAT6). Our previous studies demonstrated that aspirin blocks trafficking of STAT6 into the nucleus and thereby prevents IL-4-mediated induction of these transcripts, thereby suggesting a modality by which aspirin desensitization could provide therapeutic benefit for AERD patients.

CONCLUSION

This review will examine the evidence supporting this model.

Upper airways in aspirin-exacerbated respiratory disease

PURPOSE OF REVIEW

This review updates the status of chronic rhinosinusitis with nasal polyps (CRSwNP) in aspirin-exacerbated respiratory disease (AERD) in the contexts of epidemiology, diagnosis, pathogenesis, and treatment.

RECENT FINDINGS

Recent studies have shown that prostaglandin E₂ (PGE₂) deficiency induces an AERD phenotype in PGE₂ synthase-1 knock-out mice and also PGE₂ resistance in granulocytes of AERD patients. The numbers of platelet-adherent leukocytes increase in AERD patients, enhancing production of cysteinyl leukotrienes (CysLTs) via transcellular metabolism of arachidonate. INF-γ released from eosinophils of the sinus tissue of AERD patients promotes eosinophil maturation, increases leukotriene-associated gene expression, and releases CysLTs. The serum periostin level has been suggested to be a useful biomarker predicting the AERD/CRSwNP phenotype. Aspirin desensitization was reported to decrease the levels of CD4⁺ T cell-derived cytokines, including INF-γ and IL-10, in line with the newly defined role of INF-γ in AERD.

SUMMARY

Recent findings further support the notion that arachidonic acid metabolism is dysregulated in AERD patients. This is reflected by resistance to PGE₂, overproduction of CysLTs by enhanced numbers of platelet-adherent leukocytes, and cellular stimulation by INF-γ released from eosinophils. Aspirin desensitization may be a useful treatment option in AERD patients exhibiting recalcitrant CRSwNP.

Aspirin-exacerbated respiratory disease: characteristics and management strategies

Aspirin-exacerbated respiratory disease is a clinical entity comprising chronic rhinosinusitis with nasal polyposis, asthma and intolerance to COX-1 inhibiting drugs. The pathogenesis is not completely understood at this point, but abnormal arachidonic acid metabolism is a key feature in this syndrome. The diagnosis is confirmed only by direct drug challenge. Aspirin desensitization followed by daily aspirin therapy is a useful treatment option in these patients. In this review article are discussed the important characteristics and treatment of aspirin-exacerbated respiratory disease.

The role of leukotrienes in allergic diseases

Leukotrienes (LTs), both LTB4 and the cysteinyl LTs (CysLTs) LTC4, LTD4 and LTE4, are implicated in a wide variety of inflammatory disorders. These lipid mediators are generated from arachidonic acid via multistep enzymatic reactions through which arachidonic acid is liberated from membrane phospholipids through the action of phospholipase A2. LTB4 and CysLTs exert their biological effects by binding to cognate receptors, which belong to the G protein-coupled receptor superfamily. LTB4 is widely considered to be a potent chemoattractant for most subsets of leukocytes, whereas CysLTs are potent bronchoconstrictors that have effects on airway remodeling. LTs play a central role in the pathogenesis of asthma and many other inflammatory diseases. This review will provide an update on the synthesis, biological function, and relevance of LTs to the pathobiology of allergic diseases, and examine the current and future therapeutic prospects of LT modifiers.

Altered inhibitory function of the E-type prostanoid receptor 4 in eosinophils and monocytes from aspirin-intolerant patients

Prostaglandin (PG) E2 has been implicated in the pathogenesis of aspirin-exacerbated respiratory disease (AERD). E-type prostanoid (EP) receptor 4 is known to confer inhibitory signals to eosinophils and monocytes, amongst others. In this study, we investigated whether the responsiveness of eosinophils and monocytes to PGE2 and EP4 receptor activation is altered in AERD patients. While the expression of the EP4 receptor in eosinophils was unaltered in AERD patients, inhibition of eosinophil chemotaxis by PGE2 or the EP4 agonist CAY10598 was less pronounced in AERD patients as compared to healthy control subjects. In monocytes, we found no changes in basal or lipopolysaccharide (LPS)-stimulated PGE2 synthesis, but the response to EP4 receptor activation with respect to inhibition of LPS-induced tumor necrosis factor-α release was reduced in AERD patients, especially in the presence of aspirin (acetylsalicylic acid). Our data point towards a decreased sensitivity of inhibitory EP4 receptor that may play a role in AERD.

Aspirin or other nonsteroidal inflammatory agent exacerbated asthma

Aspirin-exacerbated respiratory disease (AERD) is an asthma phenotype with a prevalence that ranges from 2% to 25% of the asthma population. The 2% prevalence applies to patients with mild and 25% to severe, persistent asthma. COX-1-inhibiting nonsteroidal anti-inflammatory drugs, including aspirin, aggravate the preexisting upper and lower respiratory disease, sometimes in a life-threatening manner. The upper airway disease is characterized by an eosinophilic, hyperplastic rhinosinusitis with polyps. Eosinophilia, both peripheral and in the airways with Th2 inflammation, characterizes this disease. The role of allergic sensitivity in AERD is unclear, even though more than 30% of affected patients produce specific IgE to environmental allergens. Clinically, the respiratory symptoms are not usually associated with allergen exposure. The mechanism responsible for this phenotype is likely related to leukotriene (LT) metabolism because patients who are affected compared with patients who were aspirin tolerant, produce greater amounts of cysteinyl LTs. The synthesis of cysteinyl LTs is further increased after aspirin challenge and symptom exacerbation. Eosinophilia as well as a variety of other biologic markers, for example, Th2 cytokines, peripheral blood periostin, and LT enzymes and receptors, are associated with AERD both in the blood and in respiratory mucosa. These markers may help identify patients with AERD, but aspirin or other nonsteroidal anti-inflammatory drugs challenge is the primary means to confirm the diagnosis. A variety of single nucleotide polymorphisms and genes are associated with AERD, but the studies to date are limited to select populations and have not conclusively demonstrated a uniform genetic pattern in subjects with this disease. Treatment of AERD can be challenging because the nasal symptoms, including polyposis, are often refractory to both surgery and medical treatment, and the asthma can be difficult to control. Aspirin desensitization, followed by daily aspirin administration, can improve both upper and lower respiratory tract symptoms in up to 60% of individuals.